<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
    <button>按钮1</button>
    <button>按钮2</button>
    <button>按钮3</button>
    <button>按钮4</button>
    <button>按钮5</button>
    <script>
      var But = document.querySelectorAll("button");
      
      for(var i=0; i<But.length; i++){
        But[i].onclick = function(){
            alert(this.innerText);
        }
      }
    </script>
</body>
</html> 